This is 3D Nightmares, A 1996 CD by CD Factory, It contains levels for 5 Games:Doom, Duke Nukem 3D, Descent 2, WarCraft II, and Command & Conquer and a unique User interface, This File is not by me and I do not take credit for it either, This file was originally on Archive.org
To run Command & Conquer maps you must place the files in the C&C folder where Missions are, Running Levels in Descent 2 requires you to work on and edit the Game's map folder, Running WarCraft II maps requires placing the TXT and PUD files in the Mission folder,
To run Duke 3D maps you need either the 20th Anniversary World Tour or Megaton Edition, or a sourceport like Eduke32, Running Doom wads requires the Collector Edition Launcher or A sourceport such as GzDoom, ZDoom, or Chocolate Doom.